The English translation of the Bhikkhu-vibhanga: the first part of the Suttavibhanga, which itself is the first book of the Pali Vinaya Pitaka, one of the three major ‘baskets’ of Therevada canonical literature. It is a collection of rules for Buddhist monks.
The English translation of the Vinaya-pitaka (first part, bhikkhu-vibhanga) contains many...

Monks’ Training (Sekhiya) 57

Bu-Sk.57.1.1 … in Anāthapiṇḍika’s monastery. Now at that time the group of six monks taught dhamma to (someone) with a sunshade in his hand. Those who were modest monks … spread it about, saying: “How can this group of six monks teach dhamma to (someone) with a sunshade in his hand?” …

“Is it true, as is said, that you, monks, taught dhamma to (someone) with a sunshade in his hand?”

The enlightened one, the lord, rebuked them, saying: “How can you, foolish men, teach dhamma to (someone) with a sunshade in his hand? It is not, foolish men, for pleasing those who are not (yet) pleased … And thus, monks, this rule of training should be set forth:

‘I will not teach dhamma to (someone) with a sunshade in his hand,’ is a training to be observed.”

And thus this rule of training for monks came to be laid down by the lord.

Bu-Sk.57.1.2 At that time monks were (too) scrupulous to teach dhamma to (someone) who was ill (and) had a sunshade in his hand. Vin.4.200 People … spread it about, saying: “How can these recluses, sons of the Sakyans, not teach dhamma to (someone) who is ill (and) has a sunshade in his hand?”

Monks heard these people who … spread it about. Then these monks told this matter to the lord. Then the lord, on this occasion, in this connection, having given reasoned talk, addressed the monks, saying:

“I allow you, monks, to teach dhamma to (someone) who is ill (and) has a sunshade in his hand. And thus, monks, this rule of training should be set forth:

‘I will not teach dhamma to (someone) who is not ill (and) who has a sunshade in his hand,’ is a training to be observed.”

Sunshade[1] means: there are three (kinds of) sunshade: white sunshade,[2] sunshade of matting, sunshade of leaves; fastened at the middle, fastened to the rim.[3]

Dhamma means: spoken by the enlightened one, spoken by disciples, spoken by seers, spoken by devatas, connected with the goal, connected with dhamma.[4]

BD.3.142Should teach means: if he teaches by line, for every line there is an offence of wrong-doing. If he teaches by syllable, for every syllable there is an offence of wrong--doing.[5]

Dhamma should not be taught to (someone) who has a sunshade in his hand (and) who is not ill. Whoever out of disrespect teaches dhamma to (someone) who has a sunshade in his hand (and) who is not ill, there is an offence of wrong-doing.

There is no offence if it is unintentional, if he is not thinking, if he does not know, if he is ill, if there are accidents, if he is mad, if he is the first wrong-doer